Thank you for answering my question! You seem to say that the free diagnostic exam are usually of lower quality/more difficult than the other practice exams on sale? I do consider buying a packet of practice exams from one of the third parties but I'm still a bit nervous given so many choices and so many different opinions about which one is best.
Thank you.
No, they are not of lower quality. They are just more difficult in order to deflate your score, in an attempt to sell you services. Companies that sell packs of tests separately don't have the same motivation, so the scoring is more realistic. The problem is still that they are trying to mimic what AAMC does, but they are not AAMC, so the tests will be never be truly representative, and the scoring always seems to be at least a little deflated across the board.
There is nothing wrong with them, and they are useful to provide additional practice and to help highlight areas of potential weakness. Because the scoring is unreliable, my advice is to not stress about that, and to rely solely on AAMC test scores to gauge where you are and what to expect on the real thing. I used Altius. Others use NextStep (now called Blueprint), which is reputed to be a little better, but there really is no "best," since opinions are subjective.
The important thing is to master content and how to take the test. Some people swear by prep courses. Others think they are a total waste of time and money. Some people think third party FLs are invaluable, others think they are useless. Some people need months to review content. Others think that is pointless and the best prep is to just jump into practice questions. Some people love Anki decks, others don't like them. There are multiple effective roads to get there, different things work for different people, depending on their learning style and academic background. Nothing, other than AAMC material, is "best." Good luck!!!